First, your work day is almost completely sedentary. Second, you are not near friends, gyms, fields, or other systems which promote healthy activity outside of work. While diet is important for all of us, it is especially important in this circumstance.

"Healthy foods" are going to be largely inaccessible through long sparsely-populated stretches of the country. Even where they are available - in markets, fruit stands, etc. pulling your huge truck off the road to park is expensive (in terms of time) and difficult (in terms of space). Truck stops have the infrastructure for your truck. But their food selection is mostly junk.